Ingot mould and method of making



May 31, 1960 J. c. KRUGER INGOT MOULD AND METHOD OF MAKING 2 Sheets-Sheet 1 Filed Nov. 22, 1952 INVENTOR.

5 ATTORNEY INGoT MOULD AND METHOD OF MAKING John C. Kruger, Woodbridge, NJ.; Susan Kruger, Elizabeth Westphal and Elsie Kravits, Woodbridge, N.J., executrices of said John C. Kruger, deceased Filed Nov. 22, 1952, Ser. No. 322,049

2 Claims. (Cl. 2-544) This invention relates to the moulding of ingots and more particularly to an improved mould and a method of making it. A primary aim of the invention is the construction of an ingot mould adapted repeatedly to withstand the high temperature of molten metal without injurious distortion. 7

A further aim of the invention is to construct an ingot mould for use in conjunction with a water-cooling jacket or enclosure and in which practical provision is made for allowing the mould to elongate and contract while maintaining the jacketing enclosure effectively sealed against leakage of the cooling medium. The mould apparatus is disclosed and claimed in my divisional application Serial No. 378,447, filed September 4, 1953, now Patent No. 2,762,097.

Still another aim of the invention is the development of a practical process of producing a smooth true, interior finish to the mould whereby not only to facilitate removal of the ingot but to reproduce on the ingot a smooth surface devoid of wrinkles, pockets or other surface blemishes that ultimately are reflected in the product when the ingot is subsequently rolled or drawn.

In attaining the objectives of the invention it is proposed to construct the mould in the form of a long tube,

a which may be round, square, or other suitable crosssection, and to circulate a cooling medium such as water around substantially the entire length of the tube. In the instant disclosure the tube is on the order of five feet long and approximately four inches square, with rounded corners. This tube has a wall thickness of one-half inch, and is formed with a gradual taper, on the order of A; inch in the five foot length. One end of the tube, preferably the larger end, has a flange welded thereto which may be bolted to a similar flange provided atthe end of a larger diametered jacketing tube. The mould tube extends within the jacket tube and is provided at its other end with a flanged portion that is turned back and forms a short skirt around and spaced from the end portion of the mould. The outer surface of the skirt portion is turned cylindrical and is fitted to the cylindrical wall portion of the jacket tube. Suitable packing material is inserted between the outer surface of the skirt portion and the inner wall of the jacket tube to provide a leakless joint but one that will allow the mould tube to elongate and contract. Water or other cooling medium is circulated through the cavity thus formed between the inner and the outer tubes and as this cavity extends substantially the entire length of the mould the mould is caused to be uniformly chilled, i.e. there are no areas or regions of higher heat than others. Furthermore as the inverted skirt portion of the central tube is spaced from the tube, the cooling medium is caused to reach the very end of the mould, and since the expansion joint and the packing material operates along the exterior of the skirt a short distance from the end, the same cooling medium tends to keep the skirt cool and the packing from burning out. Prior to this invention attempts were made to provide the water seal directly on the mould tube itself, where because of the high heats 2,938,263 Patented May 31, 1969 and resulting tube expansion, the tube would be distorted before water-tightness could be maintained. When a tubular mould has become distorted the ingot can be removed only with extreme difficulty and with the possibility of further distortions brought about by the hammering resorted to in attempting to release the ingot.

A mould for ingots should, therefore, be free to expand and contract, and to facilitate the release of the ingot should have its interior surface smooth and devoid of wrinkles or pockets. The taper should be slight, on the order of one-eighth inch in five feet, so as to provide a bar of substantially uniform sectional area than can be re heated uniformly and rolled or drawn uniformly. In accordance with this invention such a tube may be made by starting with a length of tube desired and which, within commercial tolerances, will be substantially uniform in its dimensions from end to end. The tube is then heated, in the case of copper to approximately 1600 F., and while hot, a gently tapered and polished mandrel is'inserted into one end. The tube and the inserted mandrel is allowed to air cool for a short period and are then quickly cooled as by water quenching. During the air cooling, the tube shrinks on to the tapered mandrel and partakes of the shape thereof and when it is subsequently quenched the differential in the coefiicient of expansion of copper and steel causes the mandrel to shrink away from the copper and release the tube. The tube is again heated and the mandrel again inserted a further distance and the assembly again cooled and quenched. These operations are repeated until the tube has completely telescoped the mandrel thereby producing the highly important smooth, unwrinkled, and gently tapered surface on the interior of the mould. Moulds that may become damaged or deformed after a period of service may be straightened and reconditioned in the same manner.

Other objects and advantages will be in part indicated in the following description and in part rendered apparent therefrom in connection with the annexed drawings.

To enable others skilled in the art so fully to apprehend the underlying features hereof that they may embody the same in the various ways contemplated by this invention, drawings depicting a preferred typical construction have been annexed as a part of this disclosure and, in such drawings, like characters of reference denote corresponding parts throughout all the views, of which:

Figure 1 of the drawings is a partial assembly of an ingot moulding apparatus embodying the invention, portions being broken away to clarify the construction. Figure 2 is a transverse sectional view through the swive journal mounting of the apparatus.

Figure 3 is a face view of the swivel journal with the mould and water jacket removed therefrom.

Figure 4 is a view of an alternative form of cap for the exit end of the mould.

Figure 5 is a representative view of the apparatus that may be employed in producing an interiorly smooth mould in accordance with the process of this invention.

Figure 6 is a series of views representing successive processing steps in producing the mould of the invention.

Referring to Figure 1, the invention is shown in connection with typical moulding apparatus in which one or more swivel moulds are employed. Each mould assembly comprises an inner tube 20 and an outer tube 10 of such relative sizes as to provide a space 21 between for the circulation of a cooling medium such as water. The outer tube 10 is provided with a 'flanged stem 22 that is removably secured, as by bolts not illustrated, to a swivel trunnion 23. The trunnion 23 is journaled in a relatively stationary support 24 and is maintained against endwise movement therein by means of a nut and washer 25 fitted to a reduced end portion 26 on the trunnion that projects through .the end wall of the support 2d.

A supply pip 27 connects ith he s pport nd communicates with an internal annular channel 28 formed therein, and the swivel trunnion 23 is formed with a radial port 2 9 in the plane of the channel 28. P03 29 communicates with a longitudinal port 30 and the latter with another radial port 31 in a head end 23a of the trunnion. For convenience in drilling, the trunnion part 23:: may be initially made as a separate piece and then welded to the axle part 23. Radial port 31 communicates with a pipe line 32 that leads to one end of the chamber 21 between the tubes 10 and 26.

A return pipe 27a also is connected with the relatively stationary bearing 24 and communicates with another internal annular channel 28a thereof. Trunnion 23 is also formed with another set of ports 29a, 30a, 31a similarv to but separate from those previously described, which communicates with pipe line 32a and the other end of the chamber 21 between the two tubes. By these means water under pressure may be caused to circulate between the tubes in any angular position of the mould in relation to the support 24.

The inner tube 20, which is the mould tube, is gently tapered throughout its length, and one end, preferably its larger end, is provided with a welded-on flange 11 adapted to be bolted fast to a similar flange 35 provided at one end of the outer tube 10. In the form illustrated in Figure l, the flange 11 and tube 10 are recessed as at 12 to receive a toe end-cap 13. The cap 13 shoulders on the bottom of the recess 12 and is formed with a tapered cavity 13a that produces a tapered lead on the ingot for roll gripping, The cap 13 may be removably secured to the mold as by a straddling strap 14 and hand screw 15 arranged to operate in the strap and against the cap.

in Figure 4 a hinged cap construction is illustrated in which the tube flange 11 is provided with pivot lugs 16 and a pair of bail lugs 17., A cover member 18 is pivoted as at 18a to the lugs 16 and is formed with a toe cavity 19 that registers with the tube when the cap is closed, as shown. The cover member 18 also carries a cap-tightening cam ilfib that progressively enlarges from a starting point near the pivot 13a toward a finishing point slightly beyond the central longitudinal axis of the tube assembly. The lugs 17 on the flange 11 form pivot anchors'for a bail wire 17a that is constructed to overlay the earn 181). Movement of the bail circumferentially along the cam surface will thus effect a clamping or unclamping of the hinged cap 18.

The opposite end of the mould tube 10 is formed with an integral flange or skirt 4 that extends part way back from the. end of the tube and isspaced therefrom so as toprovide a chamber 41 between the skirt and the tube in open communication with the chamber 21 between the tubes and 20. The outer surface of the inverted flange 40 is finished cylindrical and slidingly fitted to the outer tube 10. To provide a water seal and an expansible joint, the outer tube is recessed as. at 20a to receive a packing gland ring Zilb and a packing material 20c. A complementary packing gland ring Nd is inserted on the packing material 20c and drawn up relativelyv tight by means of screws 28:; that are screw threaded into a flange 2% on the end of the outer tube 20. As the screws-2lle are tightened the packing niaterial 20c is compressed in the annular pocket defined by the outer wall of the skirt 40, inner wall of tube it), and the opposedend walls of the rings 28b and 2M, and an effective yet expansible seal is provided at that end .of the water chamber. it will be seen that the seal of this invention is. spaced from the mould proper andnot in direct contact therewith, that the cooling medium may circulate to the extreme end of the mould whereby to e. u -uu. .q n c o ing ff h ho the len th oi t e ingot. t a h tnwld p ope m y n a e an -.tlie-pseking material need be only moderate because the i reely. nd that h lampi o c pp ed o land ismaiutaiuesl relatively ool, an s ch for e a may be applied, has no distorting effect upon the mould proper.

When the apparatus has been set up and is ready for use, a funnel or pouring cap 36 is placed upon the open end of the mould. The can 36 functions also as a riser, and is fashioned with a pilot extension -37 that centers the cap with the bore of the mould tube, and with a perforated partition wall 38 for screening out slag. If desired, side lugs 39 may be provided on the cap by which it may conveniently be handled. A smooth straight bore in the mould tube is a critical factor in the casting of an ingot, and l have found that the best way to construct such a mould is to form the mould from a section of seamless tubing and to produce a gentle taper therein from end to end, by progressively deforming the tube. Figure 5 illustrates typical apparatus that may be employed, and Figure 6 successive steps of the tapering process. in the drawing, the numeral 50 represents a furnace having a heating chamber long enough to accommodate one or more tubes side by side. The furnace may be heated by gas, oil, or electricity as may be desired. The numeral 52 denotes a stationary shelf at the floor level of the heating chamber. The shelf 52 is provided with a drop-leaf extension or tube-cradle 53, illustrated in its dropped position in full lines and in its ropped up position in dotted lines in Figure 5. In the propped up position the floor of the cradle, which may be constituted of a series of rollers 54, is approximately level with the surface of the stationary shelf 52. The cradle 53 is pivoted to the shelf as at 55, is formed with spaced side walls 56 and a transversely extending end wall 57. The end wall 57 is apertured at its center to permit passage of a forming mandrel, but not the tube. A plain tube 51 is placed in the furnace and heated to a temperature of approximately 1600 F.

When the tube has been heated to the desired temperature it is withdrawn from the furnaces on to the stationary table 52 and pivoted cradle 53 and strapped in the latter by means of a slotted key 58. The key 58 interlocks with the side walls of the cradle and overlays the tube therein. The pivot point 55 is approximately at the center of the length of the strapped in tube and after removing a prop (not shown) the cradle is lowered to the full line position and the tube then stands upright on end shelf 57. With the hot tube in an upright position, a tapered steel mandrel 60 is hoisted over the tube and lowered into its open end. The mandrel 60 is planed smooth with a taper on the order of /3 inch in five feet, and its small end is given an additional taper or lead for approximately the first six inches to facilitate the entrance into the end of the tube. The mandrel is made preferably of solid steel and is, therefore, quite heavy. After the leading end has been lowered into the tube, the hoisting cable or rope is released and the mandrel allowed to fall as far as it will go into the heated tube, which, under normal conditions, will be from 12-14 inches. In this condition, the tube and mandrel are allowed to stand for a period of approximately 5 minutes. During this period the tube is cooling somewhat and shrinks tightly on the tapered mandrel, and the mandrel is absorbing some of the heat and expands slightly. After the elapse of the five minute period for air cooling the gate latch 58 is removed and the mandrel and tube hoisted out of its cradle 53 and quickly water quenched in the adjacent quench tank 7i). The tube and mandrel are allowed to remain in the quench tank for approximately five minutes, during which the process of contraction of the tube on the mandrel is arrested and the copper sets while the mandrel continues to contract because it gives up its absorbed heat more slowly. After about five minutes in the quench, the mandrel and tube is hoisted out of the quench and lifted into the cradle 53, but held slightly away from the foot plate 57. With proper timing of the air cooling and water quenching steps of the process, the tube when placed in the cradle and latched, will slide off the mandrel relatively easily. Rapping the upper end will cause the tube to fall should one stick. When the tube is free, the mandrel is hoisted the rest of the way out, and tube returned to the furnace for reheating.

Figure 6-A represents the mandrel and tube during the first stage of the tapering process.

When the partially tapered tube has been reheated to the desired temperature, it is again withdrawn from the furnace, latched to the cradle 53, and up-ended as before. The mandrel 60 is again lowered into the tube and allowed to fall and this time it will fall about halfway the length of the tube after which the telescoped assembly is air-cooled five minutes and then quenched five minutes as before explained. The tube is returned to the cradle 53, dislodged from the mandrel and returned to the furnace for a third heating.

The heating of the tube, dropping in of the mandrel, the shrinking and quenching operations are repeated as many times as may be necessary progressively to taper the tube its full length. I have found that the tapering of a tube 53 inches long usually requires four such shrinking processes (A, B, C and D in Fig. 6) to complete it to the stage where the lead end of the mandrel is caused to project about six inches out of the lower end of the tube. Other lengths of tubes will require a proportionate number of processings.

When the tube has been tapered its full length, the mandrel is removed and flange 11 welded to the large end and the inverted flange or skirt 40 welded to the small end, and the assembly otherwise machined and made ready for use in the water-jacket tube as hereinbefore explained.

Without further analysis, the foregoing will so fully reveal the gist of this invention that others can, by applying current knowledge, readily adapt it for various utilizations by retaining one or more of the features that, from the standpoint of the prior art, fairly constitute essential characteristics of either the generic or specific aspects of this invention, and therefore, such adaptations should be and are intended to be, comprehended within the meaning and range of equivalency of the following claims.

Having thus revealed this invention, I claim as new and desire to secure the following combinations and elements, or equivalents thereof, by Letters Patent of the United States:

1. The method of forming a tapered metal tube to render it suitable for use as an ingot mould which consists in heating a substantially parallel-walled heavy-gauge copper tube of the length desired for the mould to a temperature below the melting point of the metal but sufliciently high enough as to cause the tube to expand circumferentially removing the tube from the heat and inserting a tapered and relatively cool steel mandrel into the open end of the heat-expanded tube in intimate contact therewith as far as it will go, the said mandrel being of such size and mass in relation to the heavy-gauge cop per tube that it absorbs heat from the copper tube causing it to expand slightly then allowing the heat-expanded copper tube to air cool on the tapered mandrel for a selected period of time and in cooling shrink on and conform to the tapered surface of the mandrel simultaneous ly transferring part of its heat to the relatively cool steel mandrel so that the temperature of the latter approaches the temperature of the copper tube during the air-cooling period, then immersing both tube and inserted mandrel in a liquid quenching medium to arrest the shrinking of the tube and thereafter to extract absorbed heat from the mandrel whereby to cause the latter to contract slightly and to free itself from the walls of the tube, then removing the tube and mandrel from the quench medium and withdrawing the tapered mandrel from the correspondingly tapered tube.

2. The method of claim 1 in which the tube-heating, mandrel-inserting, air-cooling, quenching, and mandrel withdrawing operations are repeated until the copper tube has become tapered its full length and as such is suitable for use as a mold for the casting of billets.

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